threads

, pthreads

Synopsis

POSIX

cc –mt [ flag... ] file... [ -lrt library... ]

#include <pthread.h>

Solaris

cc –mt [ flag... ] file... [ library... ]

#include <sched.h>

#include <thread.h>

Description

POSIX and Solaris threads each have their own implementation within libc(3LIB). Both
implementations are interoperable, their functionality similar, and can be used within the same
application. Only POSIX threads are guaranteed to be fully portable to other
POSIX-compliant environments. POSIX and Solaris threads require different source, include files and
linking libraries. See SYNOPSIS.

Similarities

Most of the POSIX and Solaris threading functions have counterparts with each
other. POSIX function names, with the exception of the semaphore names, have
a “pthread” prefix. Function names for similar POSIX and Solaris functions have
similar endings. Typically, similar POSIX and Solaris functions have the same number and
use of arguments.

Differences

POSIX pthreads and Solaris threads differ in the following ways:

POSIX threads are more portable.

POSIX threads establish characteristics for each thread according to configurable attribute objects.

Solaris threads implement daemon threads, for whose demise the process does not wait.

Function Comparison

The following table compares the POSIX pthreads and Solaris threads functions. When
a comparable interface is not available either in POSIX pthreads or
Solaris threads, a hyphen (–) appears in the column.

Functions Related to Creation

POSIX

Solaris

pthread_create()

thr_create()

pthread_attr_init()

–

pthread_attr_setdetachstate()

–

pthread_attr_getdetachstate()

–

pthread_attr_setinheritsched()

–

pthread_attr_getinheritsched()

–

pthread_attr_setschedparam()

–

pthread_attr_getschedparam()

–

pthread_attr_setschedpolicy()

–

pthread_attr_getschedpolicy()

–

pthread_attr_setscope()

–

pthread_attr_getscope()

–

pthread_attr_setstackaddr()

–

pthread_attr_getstackaddr()

–

pthread_attr_setstacksize()

–

pthread_attr_getstacksize()

–

pthread_attr_getguardsize()

–

pthread_attr_setguardsize()

–

pthread_attr_destroy()

–

–

thr_min_stack()

Functions Related to Exit

POSIX

Solaris

pthread_exit()

thr_exit()

pthread_join()

thr_join()

pthread_detach()

–

Functions Related to Thread Specific Data

POSIX

Solaris

pthread_key_create()

thr_keycreate()

pthread_setspecific()

thr_setspecific()

pthread_getspecific()

thr_getspecific()

pthread_key_delete()

–

Functions Related to Signals

POSIX

Solaris

pthread_sigmask()

thr_sigsetmask()

pthread_kill()

thr_kill()

Functions Related to IDs

POSIX

Solaris

pthread_self()

thr_self()

pthread_equal()

–

–

thr_main()

Functions Related to Scheduling

POSIX

Solaris

–

thr_yield()

–

thr_suspend()

–

thr_continue()

pthread_setconcurrency()

thr_setconcurrency()

pthread_getconcurrency()

thr_getconcurrency()

pthread_setschedparam()

thr_setprio()

pthread_getschedparam()

thr_getprio()

Functions Related to Cancellation

POSIX

Solaris

pthread_cancel()

–

pthread_setcancelstate()

–

pthread_setcanceltype()

–

pthread_testcancel()

–

pthread_cleanup_pop()

–

pthread_cleanup_push()

–

Functions Related to Mutexes

POSIX

Solaris

pthread_mutex_init()

mutex_init()

pthread_mutexattr_init()

–

pthread_mutexattr_setpshared()

–

pthread_mutexattr_getpshared()

–

pthread_mutexattr_setprotocol()

–

pthread_mutexattr_getprotocol()

–

pthread_mutexattr_setprioceiling()

–

pthread_mutexattr_getprioceiling()

–

pthread_mutexattr_settype()

–

pthread_mutexattr_gettype()

–

pthread_mutexattr_setrobust_np()

–

pthread_mutexattr_getrobust_np()

–

pthread_mutexattr_destroy()

–

pthread_mutex_setprioceiling()

–

pthread_mutex_getprioceiling()

–

pthread_mutex_lock()

mutex_lock()

pthread_mutex_trylock()

mutex_trylock()

pthread_mutex_unlock()

mutex_unlock()

pthread_mutex_destroy()

mutex_destroy()

Functions Related to Condition Variables

POSIX

Solaris

pthread_cond_init()

cond_init()

pthread_condattr_init()

–

pthread_condattr_setpshared()

–

pthread_condattr_getpshared()

–

pthread_condattr_destroy()

–

pthread_cond_wait()

cond_wait()

pthread_cond_timedwait()

cond_timedwait()

pthread_cond_signal()

cond_signal()

pthread_cond_broadcast()

cond_broadcast()

pthread_cond_destroy()

cond_destroy()

Functions Related to Reader/Writer Locking

POSIX

Solaris

pthread_rwlock_init()

rwlock_init()

pthread_rwlock_rdlock()

rw_rdlock()

pthread_rwlock_tryrdlock()

rw_tryrdlock()

pthread_rwlock_wrlock()

rw_wrlock()

pthread_rwlock_trywrlock()

rw_trywrlock()

pthread_rwlock_unlock()

rw_unlock()

pthread_rwlock_destroy()

rwlock_destroy()

pthread_rwlockattr_init()

–

pthread_rwlockattr_destroy()

–

pthread_rwlockattr_getpshared()

–

pthread_rwlockattr_setpshared()

–

Functions Related to Semaphores

POSIX

Solaris

sem_init()

sema_init()

sem_open()

–

sem_close()

–

sem_wait()

sema_wait()

sem_trywait()

sema_trywait()

sem_post()

sema_post()

sem_getvalue()

–

sem_unlink()

–

sem_destroy()

sema_destroy()

Functions Related to fork( ) Clean Up

POSIX

Solaris

pthread_atfork()

–

Functions Related to Limits

POSIX

Solaris

pthread_once()

–

Functions Related to Debugging

POSIX

Solaris

–

thr_stksegment()

Locking

Synchronization

Multithreaded behavior is asynchronous, and therefore, optimized for concurrent and parallel
processing. As threads, always from within the same process and sometimes
from multiple processes, share global data with each other, they are not
guaranteed exclusive access to the shared data at any point in time. Securing
mutually exclusive access to shared data requires synchronization among the threads.
Both POSIX and Solaris implement four synchronization mechanisms: mutexes, condition variables, reader/writer
locking (optimized frequent-read occasional-write mutex), and semaphores.

Synchronizing multiple threads diminishes their concurrency. The coarser the grain of synchronization,
that is, the larger the block of code that is locked, the
lesser the concurrency.

MT fork()

If a threads program calls fork(2), it implicitly calls fork1(2), which replicates
only the calling thread. Should there be any outstanding mutexes throughout the
process, the application should call pthread_atfork(3C) to wait for and acquire those
mutexes prior to calling fork().

SCHEDULING

POSIX

Scheduling allocation size per thread is greater than one. POSIX supports the
following three scheduling policies:

SCHED_OTHER

Timesharing (TS) scheduling policy. It is based on the timesharing scheduling class.

SCHED_FIFO

First-In-First-Out (FIFO) scheduling policy. Threads scheduled to this policy, if not pre-empted by a higher priority, will proceed until completion. Such threads are in real-time (RT) scheduling class. The calling process must have a effective user ID of 0.

SCHED_RR

Round-Robin scheduling policy. Threads scheduled to this policy, if not pre-empted by a higher priority, will execute for a time period determined by the system. Such threads are in real-time (RT) scheduling class and the calling process must have a effective user ID of 0.

Solaris

Only scheduling policy supported is SCHED_OTHER, which is timesharing, based on the
TS scheduling class.

Errors

In a multithreaded application, EINTR can be returned from blocking system calls
when another thread calls forkall(2).

Usage

-mt compiler option

The -mt compiler option compiles and links for multithreaded code. It compiles
source files with -D_REENTRANT and augments the set of support libraries properly.